The present invention relates to power tools and, more particularly, to motors for the power tools which include flux rings.
In electric motor construction, the motor magnets must be retained on the housing or on a separate flux ring positioned within the housing. Ordinarily, these magnets have been glued or adhered to the metallic flux ring or housing. When using a flux ring, different methods have been utilized to position the flux ring and magnets in the housing. One such way is to position the flux ring within the housing and then add the magnets onto the flux ring. Another method is to generally adhere the magnets onto a flux ring and then slide the flux ring into the housing. Thus, it would be desirable to provide a flux ring with the magnets positioned on the flux ring which could be positioned into a motor housing and frictionally engage the motor housing to hold the flux ring in place during assembly.
The present invention provides the art with a flux ring which is capable of radial expansion and contraction with the magnets secured to the flux ring. In order to manufacture a motor with a flux ring, it is desirable to position the flux ring into the housing wherein the flux ring frictionally engages the interior periphery of the housing until the flux ring is secured to the housing. Also, the flux ring minimizes the gap between its ends to provide maximum magnetic flux carrying capacity.
In accordance with a first aspect of the invention, a flux ring comprises a ring member having a first and a second end. The ends are positioned with respect to one another such that the ends move towards and away from one another during compressing and expanding of the ring during assembly. At least one anchor is unitarily formed with the ring. At least one magnet is coupled with the unitarily formed anchor to couple the at least one magnet with the ring. The magnet is coupled with the ring such that the flux ring may be compressed and expanded with the at least one magnet coupled with the ring during assembly. One of the first or second ends overlaps or meshes with the other end. The at least one magnet is formed on the ring such that the magnet embeds with the anchor to couple the magnet to the ring. The first and second ends may include at least one mating or meshing projection and receiving recess. The at least one magnet is injection molded onto the ring. The anchor may be an aperture in the ring with a counter-sink. Also, the anchor may be a member unitarily formed with the ring and radially projecting from the ring. A combination of the anchors may be used.
In accordance with a second aspect of the invention, an electric motor comprises a motor can housing with a pair of end caps coupled to the motor can. A flux ring is positioned within the motor can housing. The flux ring includes a ring member having a first and a second end. The ends are positioned with respect to one another such that the ends move towards and away from one another during compressing and expanding of the ring during assembly. At least one anchor is unitarily formed with the ring. At least one magnet is coupled with the unitarily formed anchor to couple the at least one magnet with the ring. The magnet is coupled with the ring such that the flux ring may be compressed and expanded with the at least one magnet coupled with the ring during assembly. One of the first or second ends overlaps the other end. The at least one magnet is formed on the ring such that the magnet embeds with the anchor to couple the magnet to the ring. The first and second ends may include at least one mating or meshing projection and receiving recess. The at least one magnet is injection molded onto the ring. Also, the anchor may be an aperture in the ring with a counter-sink. Also, the anchor may be a member unitarily formed with the ring and radially projecting from the ring. Also, a combination of the anchors may be used. An armature assembly is positioned in the motor can housing.
In accordance with a third aspect of the invention, a power tool comprises a housing with a motor in the housing. The motor comprises a motor can housing with a pair of end caps secured to the motor can. A flux ring is positioned within the motor can housing. The flux ring includes a ring member having a first and a second end. The ends are positioned with respect to one another such that the ends move towards and away from one another during compressing and expanding of the ring during assembly. At least one anchor is unitarily formed with the ring. At least one magnet is coupled with the unitarily formed anchor to couple the at least one magnet with the ring. The magnet is coupled with the ring such that the flux ring may be compressed and expanded with the at least one magnet coupled with the ring during assembly. One of the first or second ends overlaps the other end. The at least one magnet is formed on the ring such that the magnet embeds with the anchor to couple the magnet to the ring. The first and second ends may include at least one mating or meshing projection and receiving recess. The at least one magnet is injection molded onto the ring. The anchor may be an aperture in the ring with a counter-sink. The anchor may be a member unitarily formed with the ring and radially projecting from the ring. Also, a combination of the anchors may be used. An armature assembly is positioned in the motor can housing. A power source is coupled with the housing. An activation member is coupled with the motor and the power source for energizing and de-energizing the motor. An output is coupled with the motor such that the motor drives the output during energizing of the motor.
In accordance with a fourth aspect of the invention, a method of manufacturing electrical motors comprises the steps of forming a motor can housing. A flux ring is formed having two ends such that the ends move towards and away from one another during compressing and expanding of the ring during assembly. A pair of magnets are coupled with unitarily formed anchors on the flux ring. The flux ring is compressed, if necessary, with the magnets on the flux ring such that the flux ring has an external diameter smaller than an internal diameter of the motor can housing. The flux ring is inserted into the motor can housing. The flux ring is expanded to frictionally engage the motor can housing. The expanding of the flux ring occurs in response to the release of the compression force on the flux ring. The flux ring is secured to the motor can housing preferably by welding, clinching, fasteners or glue. A first motor cap assembly is secured to the motor can housing. A motor armature assembly is inserted into the flux ring in the motor can housing. A second end cap is coupled with the armature assembly and the motor can housing. The magnets are injection molded onto the flux ring. The flux ring is formed such that the first and second ends overlap one another in the expanded condition in the motor can housing. A portion of the overlapped ends are welded to the housing to secure the flux ring in the motor can housing.
In accordance with a fifth aspect of the invention, a method of manufacturing a power tool comprises the steps of forming a motor can housing. A flux ring is formed having two ends such that the ends move towards and away from one another during compressing and expanding of the ring during assembly. A pair of magnets are coupled with unitarily formed anchors on the flux ring. The flux ring is compressed, if necessary, with the magnets on the flux ring such that the flux ring has an external diameter smaller than an internal diameter of the motor can housing. The flux ring is inserted into the motor can housing. The flux ring is expanded to frictionally engage the motor can housing. The expanding of the flux ring occurs in response to the release of the compression force on the flux ring. The flux ring is secured to the motor can housing preferably by welding, clinching, gluing, mechanical fastening or the like. A first motor cap assembly is secured to the motor can housing. A motor armature assembly is inserted into the flux ring in the motor can housing. A second end cap is coupled with the armature assembly and the motor can housing. The magnets are injection molded onto the flux ring. The flux ring is formed such that the first and second ends overlap or mesh with one another in the expanded condition in the motor can housing. A portion of the overlapped or meshed ends are secured to the housing to fix the flux ring in the motor can housing. A housing half is provided. The motor is positioned in the housing half. An output is positioned in the housing half and coupled with the motor. An activation member is positioned in the housing half and electrically coupled with the motor and the power source to energize and de-energize the motor which in turn drives the output. A second housing half is coupled with the first housing half to form the power tool. A power source is coupled with the housing and electrically coupled with the motor.
Additional objects and advantages of the invention will become apparent from the detailed description of the preferred embodiment, and the appended claims and accompanying drawings, or may be learned by practice of the invention.